Membrane electrode assembly manufacturing process

Abstract

Methods and compositions for making fuel cell components are described. In one embodiment, the method comprises providing a substrate, and forming or adhering an electrode on the substrate, wherein the forming includes depositing an aqueous mixture comprising water, a water-insoluble component, a catalyst, and an ionomer. The water-insoluble component comprises a water-insoluble alcohol, a water-insoluble carboxylic acid, or a combination thereof. The use of such water-insoluble components results in a stable liquid medium with reduced reticulation upon drying, reduced dissolution of the substrate, and reduced penetration of the pores of the substrate.

We claim: 
     
       1. An aqueous mixture composition for forming a fuel cell electrode, the composition comprising:
 a) water; 
 b) a water-insoluble component comprising a water-insoluble alcohol; 
 c) a catalyst; and 
 d) an ionomer,
 wherein the water is present in the aqueous mixture composition in an amount greater than 35 wt. %, based on a total weight of the ionomer and liquid portion of the aqueous mixture composition, and 
 wherein the water-insoluble component is present in the aqueous mixture composition in an amount of from 0.5 wt. % to 20 wt. %, based on a total weight of the ionomer and the liquid portion in the aqueous mixture composition. 
 
 
     
     
       2. The composition of  claim 1 , wherein the catalyst comprises a noble metal, a transition metal, or an alloy thereof. 
     
     
       3. The composition of  claim 1 , wherein the catalyst is a supported catalyst. 
     
     
       4. The composition of  claim 3 , wherein the supported catalyst comprises carbon. 
     
     
       5. The composition of  claim 1  wherein the catalyst is present in the aqueous mixture in an amount less than 90 wt. %, or in an amount less than 35 wt. %, or in an amount less than 9 wt. %, based on a total weight of the aqueous mixture. 
     
     
       6. The composition of  claim 1 , wherein the water-insoluble component comprises a C 5 -C 10  alcohol. 
     
     
       7. The composition of  claim 1 , wherein the water-insoluble component comprises 1-pentanol, 1-hexanol, 1-heptanol, 1-octanol, 2-ethyl-1-hexanol, 1-nonanol, 1-decanol, or a combination thereof. 
     
     
       8. The composition of  claim 1 , wherein the water-insoluble component further comprises a water-insoluble carboxylic acid. 
     
     
       9. The composition of  claim 8 , wherein the water-insoluble carboxylic acid comprises n-pentanoic acid, n-hexanoic acid, n-heptanoic, n-octanoic, n-nonanoic acid, n-decanoic or a combination thereof. 
     
     
       10. The composition of  claim 1 , wherein the water-insoluble component is present in the aqueous mixture in an amount less than 15 wt. %, or in an amount less than 10 wt. %, or in an amount less than 8 wt. %, or in an amount less than 6 wt. %, or in an amount less than 4 wt. %, based on a total weight of the ionomer and the liquid portion of the aqueous mixture composition. 
     
     
       11. The composition of  claim 1 , wherein the water-insoluble component is present in the aqueous mixture in an amount of from 1 wt. % to less than 20 wt. % or from 0.5 wt. % to 15 wt. %, or from 0.5 wt. % to 10 wt. %, or from 1 wt. % to 20 wt. %, or from 5 wt. % to 20 wt. %, or from 10 wt. % to 20 wt. %, based on a total weight of the ionomer and the liquid portion of the aqueous mixture composition. 
     
     
       12. The composition of  claim 1 , wherein the water is present in the aqueous mixture in an amount from 35 wt. % to 99 wt. %, based on a total weight of the ionomer and the liquid portion of the aqueous mixture composition. 
     
     
       13. The composition of  claim 1  wherein the ionomer is perfluorosulfonic acid. 
     
     
       14. The composition of  claim 1 , wherein the ionomer is present in the aqueous mixture in an amount less than 50 wt. %, or in an amount less than 35 wt. %, or in an amount less than 8 wt. %, or in an amount less than 0.5 wt. %, based on a total weight of the ionomer and the liquid portion of the aqueous mixture composition. 
     
     
       15. The composition of  claim 1 , wherein the composition further comprises a water-soluble compound. 
     
     
       16. The composition of  claim 15 , wherein the water-soluble compound is present in the aqueous mixture in an amount less than 50 wt. %, or in an amount less than 25 wt. %, or in an amount less than 9 wt. %, or in an amount less than 4 wt. %, based on a total weight of the ionomer and the liquid portion of the aqueous mixture composition. 
     
     
       17. The composition of  claim 15 , wherein the water-soluble compound is a water-soluble alcohol. 
     
     
       18. The composition of  claim 17 , wherein the water-soluble alcohol comprises isopropanol, tert-butanol, or a glycol ether. 
     
     
       19. The composition of  claim 18 , wherein the water-soluble compound comprises the glycol ether, and the glycol ether comprises dipropylene glycol (DPG) or propylene glycol methyl ether (PGME). 
     
     
       20. The composition of  claim 1 , wherein the composition is an emulsion. 
     
     
       21. The composition of  claim 1 , wherein the water-insoluble component comprises 1-heptanol, 1-octanol, 1-nonanol, 1-decanol, or a combination thereof. 
     
     
       22. The composition of  claim 1 , wherein the water-insoluble alcohol is present in the aqueous mixture in an amount of from 10 wt. % to 20 wt. %, based on a total weight of the ionomer and the liquid portion of the aqueous mixture composition.